02 Infiniti q45 fuel pressure dampener

[Toasterbaker]

I need some help...... I've searched everywhere for a fuel pressure dampener for this car and I can't find it anywhere I've even called the Infiniti dealership and they can't even get one any ideas? My car is pouring gas and running like crap any help would be appreciated

[EdBwoy]

Hello and welcome to the forum.

For posterity, the part is located in the FSM, EM - pg 30: http://www.nicoclub.com/service-manual? ... 002_Q45/em

I'm curious. Is this is as a result of you troubleshooting and somehow seeing that this part is leaking? Not a common failure point, from my experience.

Anyway, here are some part numbers:
1. Right damper
2. Left damper
The left/right catalog nomenclature seems to contradict what the manual calls them, but hey it should be clear once you start pulling things.

I have some M45 fuel rails in my garage, and it seems the part numbers are different, but if you get a chance to post pictures of what you have we can compare units.

[Toasterbaker]

I've dropped over 1200 bucks at auto shops to have them try and find it and I've even had all the coil packs scoped and the last place I took it to found when the car is at idle it will just start loading up on gas and he saw it doing so and found the dampener is shot when driving like normal down the road it runs like a top but at idle it chugs and loads up on gas and sometimes dies and it's very hard to start when warmed up

[EdBwoy]

...at idle it will just start loading up on gas

Please clarify this for me. It loads up meaning it gets a lot of fuel and the RPMs start rising?

What RPM is the engine running at or what range does it bounce about when idling in Park?
How about when idling in Drive with your foot on the brake?

Give us some more background please
Any check engine lights?
How many miles on your car and how long ago did this issue start?
Any rattle noises? Check these Link 1, Link 2

[Toasterbaker]

yes random cylinder misfire 145k and ever since I've owned it so about a year now and no rattling noises and it doesn't increase at idle it will pretty much flood itself out with fuel and it's the Worst at idle in drive in park it's not too bad but it's getting worse

[EdBwoy]

I typed something up yesterday, I suppose it didn't get posted.

1. I understand that the RPMs never rise. Could you please tell us what RPM the car idles at?
2. Do you smell any fuel from the engine bay?
3. Might you have ever recorded those random misfire codes? P0300 perhaps? How old are the spark plugs?

From my understanding of the system, yes a bad damper could cause misfiring issues and smoking, but in this setup I expect that to cause more of a low pressure issue rather than excessive flow to cause engine flooding. As long as the regulator on the exit is still working right.
I'll restate that - if the damper is damaged and is free flowing, then I don't expect the injectors to be free flowing as well. Unless the damper is damaged in a way that ended up resonating badly with an injector that got damaged and now stays open... This is what is going on in my mind, with the information you've provided.

Also, could you try this test: You said it is usually hard to start when it is warm. On one of these instances, plant your foot on the gas pedal all the way to the floor then try to start the car - that should clear it if it is flooded. Crank it for 5 seconds or so.
Then for the next attempt, start it as normal with your foot off the gas pedal. Does anything change?

[EdBwoy]

If you get a chance, update your location in your user control panel. This would help you in the case where you are located close to another member who could help you.

[Toasterbaker]

Ok update I did figure out what's going on I have 2 dampener's one on each front side of the fuel rail so I decided to pull the vacuum line off the passenger dampener and start the car as soon as the key was turned fuel started shooting out of the vacuum line so I plugged the line off at the dampener and the intake and it runs the best I've seen since I've owned it my question to you is...... will the non vacuum line dampener work because I can't find the vacuum line one anywhere

[EdBwoy]

The part is not cheap, but when I type the part number I provided in the links above into Google, I see some sources saying it's discontinued. These don't say. Best to call them and confirm:
1. https://www.nissaninfinitiparts.com/oem ... 22675ar21a
2. https://www.infinitipartsonline.com/oem ... 22675ar21a
3. https://www.parts.com/index.cfm?fuseact ... ght-DAMPER

In summary, I don't think it should be bad to run the left damper temporarily, but I'd try to get the correct one one more time.


This is me thinking out loud, just jump to the bolded part at the bottom
Generally, in my mind having a vacuum line means it's a pressure regulator.
The fuel return regulator works like this. Opens up at idle (high vacuum) to allow more fuel to leave the rail and go back to the tank.
Since this one is your inlet damper in this case, I'm assuming it works backwards. Closes up at idle (high vacuum) and lets in more fuel when you stomp on the gas (low vacuum)

Fuel shouldn't be coming out of the vacuum port, otherwise that would mean you were previously dumping fuel through this line into the engine intake.
So, here are my theories:
1. The inlet damper was giving you misfiring codes because you were getting excess fuel into the cylinders (how was your fuel economy?) which you have solved by capping the vac line.
AND/ OR
2. In the absence of vacuum you are getting the full force of the fuel pump through the inlet damper. You do lose some damping of your fuel line on the passenger side, but the return regulator should still keep your pressures correct.
I don't know how bad it is to run wide open in a design that was meant to be vacuum regulated, but technically using an inline damper should NOT obstruct flow. I just don't know what effect that would have in the long run